The present invention relates generally to turbine buckets and, more particularly, to a methodology to estimate bucket condition and its remaining service life utilizing an infrared camera (IR camera) that can capture the temperature distribution on the bucket. Properly integrated neural network and the utility of diagnostic techniques including signal and image processing techniques are used to estimate the bucket condition from the captured temperature distribution.
Buckets are critical gas turbine components. Unexpected failures of buckets almost always result in high maintenance costs. It is difficult to assess bucket condition and predict its remaining useful life while it is in service. The current analytical approach in estimating bucket life for temperature related failures requires absolute bucket metal temperature measurement. However, measuring the xe2x80x9cabsolutexe2x80x9d temperature is not trivial due to many uncertainties including environment effects, sensor degradation, etc.
Optical pyrometers have been used to measure the temperatures of metal surfaces. Previous studies described the application of a high resolution turbine pyrometer to heavy duty gas turbines and compared the capability of long wavelength infrared pyrometers with short infrared wavelengths. Since the pyrometer, however, measures the temperature only from a small target spot (commonly 1 mm-26 mm), the current capability of the pyrometer is limited to the xe2x80x9cline of sight (LOS)xe2x80x9d, the optical path of a turbine pyrometer. To compensate this limited capability, some researchers developed and evaluated a versatile high resolution pyrometer system and its application to radial turbine rotor temperature mapping. This approach, however, is not trivial and requires complex mechanical/electrical design. None of these studies attempted to assess the condition of the bucket that is in service.
Researchers have developed a number of diagnostic algorithms and applied them to vibration sensor output such as an accelerometer for machinery health monitoring. There is difficulty, however, in detecting the problem on the bucket surface in service using such vibration sensors. Moreover, none of the researchers attempted to apply the diagnostic concepts to optical sensors such as an IR camera and combine diagnostic techniques with image processing techniques in a turbine application.
In an exemplary embodiment of the invention, a method of estimating turbine bucket oxidation condition includes the steps of (a) measuring, with an infrared camera, a temperature distribution on a surface of at least one rotating turbine bucket; and (b) determining a condition index based on the temperature distribution, the condition index reflecting at least one of an overall condition of a bucket or a specific location on the bucket.
In another exemplary embodiment of the invention, a method of estimating turbine bucket oxidation condition and predicting remaining useful bucket life during operation of a turbine is performed by processing a surface temperature distribution measured with an infrared camera of at least one rotating turbine bucket.
In yet another exemplary embodiment of the invention, a system estimates turbine bucket oxidation condition. The system includes an infrared camera that measures a surface temperature distribution of at least one rotating turbine bucket. A processor receives output from the infrared camera and determines a condition index based on the measured surface temperature distribution. The condition index reflects at least one of an overall condition of a bucket or a specific location on the bucket.